This invention relates to panels having vacuum retaining plastic walls and more particularly to containers having double wall construction of plastic materials with an evacuated space between the walls.
It is well known to form plastic insulating panels by foaming plastic materials such as polystyrene, polyethylene, etc. Such insulating panels are often employed as insulation for refrigerators, refrigerated trucks and rail cars, picnic coolers and the like.
In view of the unsolved problems of conventional insulation panels, it would be highly desirable to provide an economical plastic vacuum panel having substantial structural strength and long-lasting thermal insulative properties that are significantly better than those of foam plastic panels.